1. Field of the Invention
The invention is generally related to lining an internal surface of a tube.
2. Description of the Prior Art
Tubes are widely used in industrial, municipal, and domestic applications as means to transport flowable materials between different locations. In many industrial applications, the tubes are used to transport chemicals under severe conditions, such as corrosive, high temperature, high pressure, and combinations of these conditions. Two primary concerns in these applications are wear and/or corrosion damage to the internal walls of tubes. Wear is a problem for tubes in general while both wear and corrosion problems can be a concern in the case of metal tubes. Every year the cost of wear and/or corrosion damage to tubes is in the many millions of dollars in terms of production down-time and tube repair or replacement work.
To address the corrosion and wear problems associated with metal tubes, for instance, the tube ideally would be formed as a composite of the two types of materials, with ceramic on the inside and metal on the outside. There are a number of conventional techniques for forming protective ceramic coatings on internal surfaces of metal tubes. Among these, a surface chemical reaction has been used to form an oxide film on the inner surfaces of metal tubes, for example, by high-temperature oxidation or low-temperature anodization. Alternatively, thin film deposition techniques, such as physical vapor or chemical vapor depositions, have been used to coat the inside surfaces of the metal tubes with a ceramic material. Thermal-sprayed deposition of ceramic coatings on the inside of the tubes also has been practiced. Additionally, shrink-fitting, i.e., heating up a metal tube followed by telescopically inserting a tubular ceramic shell inside the heated tube, has been known. Also, another technique is to dip the metal tube in a ceramic slurry to provide a ceramic coating on at least the inner surfaces of the tubes. Unfortunately, prior techniques are either expensive or time-consuming approaches for obtaining a uniformly thick ceramic film on the internal surfaces of metal tubes. Furthermore, a more versatile process is needed that not only is applicable to metal tubes, but which also could be practiced on and easily adapted to other types of tubes, such as ceramic tubes.
Sealing and lining techniques for conduits and pipes are also known from the patent literature mentioned below:
U.S. Pat. No. 4,745,879 to Shishkin et al. teaches a device for coating the internal surface of a pipeline which uses hoses, a rotating blade and a smoothing cone. A coating mixture is delivered by a flexible hose to a cone shaped member. The cone shaped member distributes the coating material on the inner surface of the pipeline and serves to smooth out the coating material to form a uniform layer.
U.S. Pat. No. 4,329,937 to Holland teaches a pipe lining apparatus wherein a pipe liner vehicle travels through the pipe applying the material as it moves through. The distributor discharges concrete out of the discharge element onto the inner surface of the pipe as the vehicle traverses in the direction indicated by the arrow. A set of rotating trowel arms smooth the mortar which has been deposited.
U.S. Pat. No. 3,966,389 to Shubert teaches a frusto-conical troweling apparatus for pipe lining. A dispensing head rotates to sling mortar against the interior surface of the pipe. The pipelining machine supplies mortar through a hose, and is pulled from right to left by any suitable means. The conical troweling device moves along with the hose and evens out the mortar on the surface.
U.S. Pat. No. 4,554,178 to Yamamoto et al. teaches a process whereby inorganic oxides are used as sealants to repair and prevent leakage in a pipeline. The sealant contains fine particles of inorganic oxide weakly adhering to one another into aggregations which can enter and plug fine cavities of the interior of a pipeline.
U.S. Pat. No. 4,774,905 to Nobis teaches an apparatus for internally coating pipes. The coating material is drawn through a pipe and fed to the rotating spraying device which atomizes the material and disperses it onto the internal surface of the pipe. The coating material is not specified in the patent.
U.S. Pat. No. 5,443,377 to Perkins et al. teaches a method and apparatus for lining a section of pipe with cement mortar. A section of the water main is lined by delivering wet mortar from a mixer to a lining apparatus, and throwing the wet cement mortar onto the cleaned surface of the water main.
U.S. Pat. No. 5,019,417 to Northcutt teaches a system for pipe lining including a forward seal and a following spreader defining a chamber therebetween for receiving flowable lining material. The spreader is immediately followed by a cylindrical elongate platen formed of radiant-energy transparent material. A radiant energy source is mounted inside the platen which emits radiant energy that is transmitted through the platen to the flowable lining material to effect or accelerate the curing of the lining material.
U.S. Pat. No. 5,326,400 to Sagawa teaches a method for coating an interior surface of an elongated pipe member using a pair of plugs. A first lead plug member has a resilient cylindrical body with an outer diameter close to an inner diameter of the pipe member, and a trailing second plug member has a cylindrical body of an outer diameter smaller than the inner diameter of the pipe member and a brush provided at an end portion of the body of the second plug member, where the brush fiber radially extend outward such that their outer ends define a cylindrical surface having a diameter close to that of the pipe diameter. The coating is applied to the interior surface of the pipe member while the two plug members proceed therethrough.
U.S. Pat. No. 5,499,659 to Naf teaches a process for sealing and internal repair of systems of laid conduits in which a sealant is first applied to the leak by either introducing a sealant into the leaky conduit by means of air, in which the sealant is a dry water-swellable bentonite, a dry hydraulically disintegrated plastic dispersion preparation, or a mixture thereof and then conduit is filled with fluid; or alternatively, the sealant is introduced into the leaky conduit by means of water where the sealant is a finely divided inert material. Next, the conduit is emptied and compressed air charged with abrasive particles is blown through the conduit. Then, the conduit is internally coated by blowing into it a solvent-free epoxy resin containing a hardener and fibers.